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An Update on Component Shielding Effectiveness Testing

An Update on Component Shielding Effectiveness Testing. Joe Butler Chomerics Division of Parker Hannifin Corp. Shielding Effectiveness. Commercial EMI Shielding Products EMI gaskets Conductive compounds Conductive coatings Shielded windows and air ventilation panels

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An Update on Component Shielding Effectiveness Testing

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  1. An Update on Component Shielding Effectiveness Testing Joe Butler Chomerics Division of Parker Hannifin Corp.

  2. Shielding Effectiveness • Commercial EMI Shielding Products • EMI gaskets • Conductive compounds • Conductive coatings • Shielded windows and air ventilation panels None of these products are typically measured by an industry consensus, shielding effectiveness test method. Vendor utilized test methods vary by manufacturer.

  3. Shielding Effectiveness Test Standards • MIL-STD-285 – Shelters - Withdrawn • MIL-DTL-83528 – Conductive Elastomer EMI Gasket Radiated Field and DC Volume Resistivity • NSA 65-6, 73-2A, 94-106 – Tempest Shelters • IEEE STD 299 – Shelters (replaced MIL-STD-285) • IEEE STD 1302 – Guide to EMI Gasket Test Methods • ASTM D 4935 – Planar Materials - Withdrawn • ASTM E1851 – Shelters (duplicates MIL-STD-285) • Reverberation Chamber Tests, TEM Cells • SAE ARP 1705 – EMI Gasket Transfer Impedance • SAE ARP 1173 – EMI Gasket Radiated Field • EN 50147-1 – Anechoic Chambers • IEC 61000-5-7 - Enclosures • VG 95373 Part 15 – Small Enclosures • SCTE 48-1-2006 – GTEM Cell Tests

  4. Shielding Effectiveness EMI Gaskets • DC volume resistivity • MIL - DTL - 83528 • SAE- AIR -1404 warning on relationship between resistivity and shielding effectiveness • Transfer impedance • SAE- ARP-1705 • Radiated field tests • MIL-DTL-83528 • MIL-STD-285 or IEEE-STD-299 Modified • Stirred mode/reverberation chamber testing • Enclosure or equipment level testing

  5. Shielding Effectiveness Conductive Compounds • DC Volume Resistivity • Joint Through-Resistance • Radiated Field Tests • MIL-STD-285 or IEEE-STD-299 Modified • Enclosure or Equipment Level Tests

  6. Shielding Effectiveness Conductive Coatings • DC surface resistivity • ohms per square @ recommended dry film thickness • ASTM D4935 – recently withdrawn • Radiated field tests • MIL-STD-285 or IEEE-STD-299 Modified • Stirred mode/reverberation chamber tests • Enclosure or equipment level tests

  7. Shielding Effectiveness Shielded Windows & Air Ventilation Panels • Radiated field tests • MIL-STD-285 or IEEE-STD-299, Modified • Stirred mode/reverberation chamber tests • Enclosure or equipment level tests

  8. Shielding Effectiveness Current standards activity • IEEE EMC Society actively working on revisions to IEEE STD 299 to create three sections addressing three sizes of enclosures • SAE AE-4 Committee has discussed revising and updating SAE ARP 1173 • ASTM Committee D09 has stopped EMC standards development activities

  9. Shielding Effectiveness MlL-STD-285 (1956) • Frequencies: 150 kHz - 200 kHz, 200 kHz, 1 MHz, 18 MHz, 400 MHz • Officially withdrawn but still used in industry • Many undocumented/unapproved derivatives used - “modified” MIL STD 285 • Used extensively to rate shielding performance of EMI gaskets, conductive coatings, shielded vents and windows

  10. Shielding Effectiveness US National Security Agency Standards - NSA 65-6, NSA 73-2A, NSA 95-106 • NSA 65-6 (1964) - 1 kHz - 10 GHz,100 dB, 10 kHz - 10 GHz • NSA 73-2A (1972) - 1 kHz - 1 GHz, 50 dB, 10 kHz - 100 MHz • NSA 94-106 (1994) - 1 kHz – 10 GHz, 100 dB, 10kHz – 10 GHz, (replaced NSA 65-6)

  11. Shielding Effectiveness IEEE STD 299 (1991) • Frequency range 9 kHz - 18 GHz, (extendable to 50 Hz and 100 GHz) • Developed to replace MIL-STD-285 • Working group actively working on revisions • Standard divided into separate parts for different size enclosures

  12. Shielding Effectiveness ASTM E 1851 (1997) • Frequency bands - 140 - 160 kHz, 14 - 16 MHz, 300 - 500 MHz, 900 - 1000 MHz, 8.5 GHz - 10.5 GHz • Developed by US military shelter manufacturers as replacement for “retired” MIL STD 285 because they felt the proposed replacement, IEEE STD 299, was too complicated

  13. Shielding Effectiveness IEC 61000-5-7 (2001) Installation and mitigation guidelines - Degrees of protection provided by enclosures against electromagnetic disturbances (EM code) • Frequency range 10 kHz - 40 GHz • Establishes shielding code designation - EMABCDEF where ABCDEF indicates 6 frequency bands where a shielding designator value from < 10 dB = 0, to > 100 dB = 9, is assigned

  14. Shielding Effectiveness IEC 61000-5-7 Setup

  15. Shielding Effectiveness • German VG 95373-15 (1998) • Bundeswehr equipment procurement • Frequency ranges: 30 Hz - 3 MHz, 30 MHz - 1 GHz • Society of Cable Telecommunications Engineers (SCTE) IPS-TP-212 (1996) • RF ingress shielding measurement • Frequencies: 54 MHz, 100 MHz, 200 MHz, 400 MHz, 700 MHz, 1000 MHz

  16. Shielding Effectiveness German VG 95373-15 Setup

  17. Shielding Effectiveness SCTE IPS-TP- 212 Setup

  18. Shielding EffectivenessASTM D 4935 Test Setup

  19. Shielding EffectivenessASTM D 4935 Test Samples

  20. Shielding EffectivenessDual TEM Cell Test Setup

  21. Shielding EffectivenessMIL-DTL-83528 Setup

  22. Radiated Test Setup Chomerics Shielding Effectiveness Test Setup

  23. Radiated Test Setup

  24. Radiated Test Setup

  25. Shielding EffectivenessSAE ARP 1173 Setup

  26. Shielding EffectivenessSAE ARP 1705 Setup

  27. Shielding EffectivenessIEEE STD 1302 Gasket Comparison of TestMethods

  28. Shielding EffectivenessStirred Mode Chamber

  29. Shielding Effectiveness Some Relevant Reference Papers • Stirred Mode – Crawford, Koepke, NBS Tech Note 1092, April 1986; Hatfield, Freyer, Rowan, 1992 & 1994 EMCS Symposium • Reverberation Chambers – Holloway, Ladbury, Coder, Koepke, Hill – EMCS Transactions, • Reverberation Chambers – Holloway, Ladbury, Koepke, Hill, Garzia – EMCS Transactions, May 2003

  30. Shielding Effectiveness Current Actions of Shielding Component Customers • Not only asking for assurances of long term reliability but detailing test protocols to qualify products, e.g., accelerated life testing - high/low temperature cycling, heat/humidity, temperature soak • More requesting UL 94 V-0 flammability ratings • Increasing amount of individual corporate “Green” initiatives prohibiting certain hazardous substances • European Union RoHS requirements • Request for detailed elemental composition of materials beyond MSDS details • Requests for shielding data against aluminum flanges with trivalent chromate treatment vs. hexavalent chromate

  31. Shielding Effectiveness Future Actions of Shielding Component Vendors • Will try to maintain the status quo • Will continue to have dwindling involvement in the SE standards development within SAE and IEEE • If reverberation chamber shielding test data is necessary, most manufacturers will use outside test labs

  32. Shielding Effectiveness Thanks for your time! Questions??? Joe Butler JButler@Parker.com 781-939-4267 www.chomerics.com

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